In a wireless communication system, because of factors such as mobility of a user equipment (User equipment, UE) and multipath propagation of a wireless signal, a channel state between a base station and the UE changes with the change of time and a frequency. In order to improve transmission efficiency of the system, it is expected that the base station can effectively utilize channel state information between the base station and the UE, and schedule each UE onto a time frequency resource corresponding to a best channel state of the UE. Based on this, the base station needs to acquire channel state information of each UE.
In a wireless communication system, such as an LTE (Long term evolution, long term evolution)/LTE-A (LTE-Advanced, long term evolution-advanced) system, a base station generally acquires a channel state between the base station and a UE through channel state information reported by the UE. Specifically, the UE may obtain, through a calculation, channel quality and an interference level between the base station and the UE by measuring a downlink reference signal sent by the base station, and further obtain downlink channel state information (Channel State Information, CSI) between the base station and the UE. Here, the downlink reference signal mainly includes a cell-specific reference signal (Cell-specific reference signal, CRS) and a channel-state information reference signal (Channel-State Information reference signal, CSI-RS). Moreover, the base station may also acquire uplink channel quality between the base station and the UE by measuring an uplink reference signal sent by the UE, such as an uplink sounding signal SRS (Sounding Reference Signal, SRS); for a system having a channel reciprocity characteristic, such as a TDD system, the base station may obtain downlink channel quality between the base station and the UE through the uplink channel quality.
In a wireless communication system, for measurement of channel state information, two factors are mainly considered for design of a reference signal. A first factor is that measurement precision can be satisfied, namely, it needs to be ensured that channel state information obtained through measurement is basically the same as an actual channel condition between a base station and a UE, so that the base station can more accurately perform rate matching on the UE, namely, can adopt a more appropriate modulation coding scheme (Modulation Coding Scheme, MCS) for data scheduling of the user and schedule the user onto a more appropriate time frequency resource; a second factor is that it needs to be considered that an overhead of the reference signal is as small as possible, so as to avoid causing an excessive waste of a data resource.
For a same UE, reference signals used on different frequency bands in a same carrier may be used for different measurement purposes, for example, used for channel quality measurement and interference level measurement separately, and reference signal characteristics required for these two types of measurement may be different. However, currently the base station does not consider different measurement purposes of different frequency bands for reference signal characteristics of frequency bands configured by the UE, and in this way, the foregoing two factors cannot be considered completely, so that precision of channel quality measurement or interference level measurement on a part of frequency bands is insufficient, or so that reference signal overheads on a part of frequency bands are increased.